I, too, would be interested to know exactly where the pain is and is it accompanied by any numbness either during or after the ride.
I got a new custom bike this past March and have struggled with bad hand pain. From my experience, hand pain can be (1) an indication that you aren't balanced between front and back. Ideally, you want most (but not all) of your weight behind your crank. (2) an indication that your reach and/or saddle-to-bar drop are off. Unfortunately, figuring out where in space your handlebars should be is no easy task as it is a function of saddle drop, saddle for and aft position, the spacers under your stem, your stem length and rise and your handlebars themselves; (3) a function of the bars themselves, how they are designed and tilted, the bartape, and your gloves; (4) an indication that you have a weak core.
Sound complicated? It is. I've been to two fitters and changed nearly every element I mentioned above, and my hands (while better) still hurt.
Live with intention. Walk to the edge. Listen hard. Practice wellness. Play with abandon. Laugh. Choose with no regret. Continue to learn. Appreciate your friends. Do what you love. Live as if this is all there is.
--Mary Anne Radmacher